A typical apparatus for generating microbubbles from a liquid by injecting gas into the liquid was introduced as follows.
In an example, Japanese Laid-Open Patent Publication No. 2006-116365 discloses “a bubble generator” which generates a mixed fluid by mixing gas into a liquid, as shown in FIG. 1.
FIG. 1 shows a cross-sectional view of the bubble generator of the related art. Referring to FIG. 1, the bubble generator includes a container body 100 having a cylindrical space, an air inlet 120 opened at one end side of the body, and a pressurized liquid inlet 140 formed in the outer circumference of the body. A gun protrudes inward from a part of the body that is adjacent to the air inlet 120 so as to form a conical or truncated conical shape 160. With this configuration, gas and liquid are mixed while being circulated inside the bubble generator, thereby forming microbubbles.
Microbubbles generated using such a bubble generator are characterized by a large specific surface area due to their small bubble size, a high inner pressure, absorptivity, and the like. Microbubbles are expected to have the effects such as water purification, physiological activation, an increase in agricultural productivity, energy savings, a decrease in frictional resistance, and the like. Therefore, studies for the application thereof are underway.
For example, microbubbles can be used for effective treatment of waste water, an increase in agricultural productivity, semiconductor cleaning, and the like. It is also possible to generate microbubbles in warm water in a bath so that the water becomes hazy like milk. This can produce the effect of bathing in a hot spring which moisturizes the skin.
Referring to FIG. 1, the bubble generator of the related art employs a structure which generates a vortex inside the bubble generator using a circulation pump.
However, the bubble generator of the related art has problems in that the generator is limited to a low-concentration type since the average diameter of bubbles that are generated thereby ranges from 30 μm to 200 μm, and in that the size and amount of bubbles are not suitably adjusted for the purpose of use.